1. Field of the Invention
This invention relates to a chemical substance detection apparatus comprising a plurality of chemically sensitive elements constructed as an insulation gate field effect transistor formed on one or different substrates and including chemically sensitive portions selectively sensitive to different specified substances and one reference electrode, at least said chemically sensitive portions as well as said one reference electrode being brought into contact with the same test substance so as to detect various specified substances in said test substance.
2. Description of the Prior Art
Various chemically sensitive elements constructed as a field effect transistor provided at its gate portion with a chemically sensitive portion which is sensitive to a specified chemical substance and can detect various kinds of ions, gas, enzyme, antibodies or the like have heretofore been proposed. Such chemically sensitive element is composed of a chemically sensitive portion formed on one semiconductor substrate and operative to be selectively sensitive to one specified chemical substance or composed of a plurality of chemically sensitive portions formed on one semiconductor substrate and operative to be selectively sensitive to different chemical substances. Various methods of detecting a specified ion concentration and activity in a test liquid such as serum or the like by means of the above mentioned chemically sensitive element such, for example, as an ion sensor have also been proposed.
On the one hand, in biochemistry field, many items of ion concentrations and activities are often measured from the same test liquid in general. In this case, as one of the measuring methods, the same test liquid is injected into a plurality of containers and respective measuring circuits are constructed for these containers and the measurement is effected by means of a multi-channel system. But, in this method, the items of ion concentration and activity are measured independently, so that this method must use much amount of test liquid and is troublesome in operation. Particularly, if use is made of an ion sensor composed of a plurality of chemically sensitive portions formed on the same semiconductor substrate and sensitive to different ions, the ability of the ion sensor could not be fully revealed. Such drawback of the ion sensor has also been encountered with a gas sensor, enzyme sensor, immunity sensor or the like.